García-Guillén Isabel M, Martínez-de-la-Torre Margaret, Puelles Luis, Aroca Pilar, Marín Faustino
Department of Human Anatomy and Psychobiology, Faculty of Medicine, Regional Campus of International Excellence "Campus Mare Nostrum", Biomedical Research Institute of Murcia (IMIB-Arrixaca), University of Murcia, Murcia, Spain.
Front Neuroanat. 2021 Dec 10;15:785840. doi: 10.3389/fnana.2021.785840. eCollection 2021.
The trigeminal column is a hindbrain structure formed by second order sensory neurons that receive afferences from trigeminal primary (ganglionic) nerve fibers. Classical studies subdivide it into the principal sensory trigeminal nucleus located next to the pontine nerve root, and the spinal trigeminal nucleus which in turn consists of oral, interpolar and caudal subnuclei. On the other hand, according to the prosomeric model, this column would be subdivided into segmental units derived from respective rhombomeres. Experimental studies have mapped the principal sensory trigeminal nucleus to pontine rhombomeres (r) r2-r3 in the mouse. The spinal trigeminal nucleus emerges as a plurisegmental formation covering several rhombomeres (r4 to r11 in mice) across pontine, retropontine and medullary hindbrain regions. In the present work we reexamined the issue of rhombomeric vs. classical subdivisions of this column. To this end, we analyzed its subdivisions in an AZIN2-lacZ transgenic mouse, known as a reference model for hindbrain topography, together with transgenic reporter lines for trigeminal fibers. We screened as well for genes differentially expressed along the axial dimension of this structure in the adult and juvenile mouse brain. This analysis yielded genes from multiple functional families that display transverse domains fitting the mentioned rhombomeric map. The spinal trigeminal nucleus thus represents a plurisegmental structure with a series of distinct neuromeric units having unique combinatorial molecular profiles.
三叉神经柱是一种后脑结构，由二级感觉神经元构成，这些神经元接收来自三叉神经初级（神经节）神经纤维的传入信息。经典研究将其细分为紧邻脑桥神经根的三叉神经主感觉核，以及脊髓三叉神经核，后者又由嘴侧、极间和尾侧亚核组成。另一方面，根据前脑节模型，该神经柱将被细分为源自各个菱脑节的节段单位。实验研究已将小鼠的三叉神经主感觉核定位到脑桥菱脑节（r）r2 - r3。脊髓三叉神经核呈现为一个多节段结构，覆盖脑桥、脑桥后和延髓后脑区域的几个菱脑节（小鼠中为r4至r11）。在本研究中，我们重新审视了该神经柱的菱脑节划分与经典划分的问题。为此，我们在一种名为后脑拓扑学参考模型的AZIN2 - lacZ转基因小鼠中分析了其划分，同时还分析了三叉神经纤维的转基因报告系。我们还筛选了成年和幼年小鼠脑中沿该结构轴向维度差异表达的基因。该分析产生了来自多个功能家族的基因，这些基因显示出与上述菱脑节图谱相符的横向结构域。因此，脊髓三叉神经核代表了一个多节段结构，具有一系列具有独特组合分子特征的不同神经节单位。
